Feeding, Substrate and Watering Methods of Walter Pall

[kcpoole]

Particle size is an interesting point.

When particle size varies I would expect smaller particles to be washed to the bottom of the pot, the bottom of the pot would then retain much more water than the surface and increase the temptation to overwater.

I have been using My diatomite / Zeolite mix for about 4 years now, and have used a particle size from 2 - 7 mm. I never worry about Grading them to size for different pots (except Mame or small Shohin trees. I will sift them to use smaller tan 3-4 mm only).

When repooting my trees, I have found that the Particles are evenly distributed thru the pot. I do not notice a higher Concentration of small bits in the bottom
I accasionally have spread a lyer of 2 mm particles over the top to see what happens, and over time they do not get "Washed to the Bottom" at all

Ken

[NBPCA]

Particle size is an interesting point.

When particle size varies I would expect smaller particles to be washed to the bottom of the pot, the bottom of the pot would then retain much more water than the surface and increase the temptation to overwater.

I have been using My diatomite / Zeolite mix for about 4 years now, and have used a particle size from 2 - 7 mm. I never worry about Grading them to size for different pots (except Mame or small Shohin trees. I will sift them to use smaller tan 3-4 mm only).

When repooting my trees, I have found that the Particles are evenly distributed thru the pot. I do not notice a higher Concentration of small bits in the bottom
I accasionally have spread a lyer of 2 mm particles over the top to see what happens, and over time they do not get "Washed to the Bottom" at all

Ken

I probably tend to agree with Ken. Smaller particles fall to the bottom only through disturbance unless the particles were very small in size in the pot in comparison(a rocky farmers field for instance where the larger rocks are disturbed and the finer material falls under and fills the gap. The larger rocks magically rise to the surface.)

Grant

[craigw60]

This point which Walter makes about particle size is nothing new to me, my friend and mentor Ian Edwards taught me many years ago that in order to achieve perfect drainage all the components of the potting mix need to be the same size, I think he learnt this while working for the forestry commission.
Craigw

[NBPCA]

This point which Walter makes about particle size is nothing new to me, my friend and mentor Ian Edwards taught me many years ago that in order to achieve perfect drainage all the components of the potting mix need to be the same size, I think he learnt this while working for the forestry commission.
Craigw

Hi Craig,

What do you use and how do you use it.

Grant

[craigw60]

I have been using diatomite for about 12 years 50/50 with pine bark debco used to make a product called super fine orchid mix which was perfect but they have not made it for years and these days I sieve potting mix, prior to the arrival of diatomite I used granite which is what Ian taught me. Discovering this mix years ago was a revelation to me and my trees responded immediately. I have been advocating this potting mix in Melb. for years but most people seem to be concerned about their trees drying out, my experience is the opposite.
Craigw

[kcpoole]

I have been advocating this potting mix in Melb. for years but most people seem to be concerned about their trees drying out, my experience is the opposite.
Craigw

I can understand excactly what you mean. I get the same response

Ken

[Grant Bowie]

I have been using diatomite for about 12 years 50/50 with pine bark debco used to make a product called super fine orchid mix which was perfect but they have not made it for years and these days I sieve potting mix, prior to the arrival of diatomite I used granite which is what Ian taught me. Discovering this mix years ago was a revelation to me and my trees responded immediately. I have been advocating this potting mix in Melb. for years but most people seem to be concerned about their trees drying out, my experience is the opposite.
Craigw

Hi Craig,

The Diatomite comes in 3 sizes; under 2mm; 2mm to 7mm; and 7mm to 15mm or larger.So unsieved or ungraded (Like QV uses.) you are probably using particles of various size; 2mm to 7mm.

The other material is organic so that is interesting; like the Pine bark Mini Nuggets 5mm to 8mm.(Stocked by Collectors Corner)

You are certainly in a wetter and cooler area in the hills of Dandenongs as opposed to those down on the flat in Melbourne where water retention in their bonsai is more important. However your mix is not all one size; but it certainly is free draining.(similarish to mine)

I am just trying to get a handle on the best mix for Canberra and also what works in your area. When you lend a tree to the NBPCA it is useful to know what it is in to judge its requirements for fert and water.

grant

[Grant Bowie]

I have been advocating this potting mix in Melb. for years but most people seem to be concerned about their trees drying out, my experience is the opposite.
Craigw

I can understand excactly what you mean. I get the same response

Ken

Hi Ken,

Yes a better understanding of mixes/diatomite or other inorganics will be usefull.

Grant

[craigw60]

I was using this mix long before I moved up here and used to live in the western suburbs with a north facing backyard, I also worked away from home so was not there to water during the day. With regards to particle size not they are not exactly the same size that would require lots of grading however they are pretty close and I sieve everything in a 1mm sieve so there is nothing smaller than that in the mix, I have looked at the mini pine bark mix but don't like the look of it it looks a little rough and the particles seem too large to me I prefer to sieve my nursery potting mix to get the correct grading.
Craigw

[Bretts]

Hey Craig
If you have been using diatomite for 12 years surely that would make you one of the first in Australia. How did you find the stuff? I remember finding this stuff on the internet 4 years ago asking one of the international guys if it would work for bonsai which got a definite sure seems like it. It used to be sold (exported from Australia by miadenwell) as RoK2 or something In America, I can never find the website anymore. I can never remember how I found the stuff but It may have been from the Rok2 testimony from bonsai growers. I know Ken was looking into the stuff about the same time and was lucky enough to have easy access to the stuff.
I started using sponglite instead from bunnings thinking it was the same thing.
I have skimmed over Grants results and not sure I agree with the results for spongelite. This stuff has given me nothing but excellent results in a mix and I inadvertently used it 100% on a trident group that was effected by fungus early this spring but has almost fully recovered compared to the two others and is powering on even though it practically drys out in between the two watering's a day that should be three. In full sun.

Hi Grant
As you know I am no expert but recently my studies and thoughts on media just does not accommodate that a mix only works in a certain area. We have people growing trees in everything from fine silt mud to 100% LARGE grade Akadama and I can find no correlation to success in wich climate they are in. How many times have I been told akadama will be no good in our climate because it is much hotter than Japan. What I believe the deciding factor on whether a medium will work for you is habit.
As Walter states if you use the mix he suggests then you must have the habit of heavy fert and heavy watering. But as Walter states he adds peat moss to keep the substrate moist for longer. If you did not want to water as often as several times a day In our drier climate then it is simply a matter of adding more peat moss (rough peat not the fine peat moss that is the only thing that seems available in Australia) or spag moss if that is not avialable.
I have to wonder in your experiments when the osmocote and liquid fert went better than liquid fert alone whether a stronger fertilising regime as Walter suggests would have changed the results.
Again maybe some do not want to use that much fert and some like Pol do not want to or able to water that much, which makes me think that horticultural habits are more important than climate when it comes to substrates.

[63pmp]

I was using this mix long before I moved up here and used to live in the western suburbs with a north facing backyard, I also worked away from home so was not there to water during the day. With regards to particle size not they are not exactly the same size that would require lots of grading however they are pretty close and I sieve everything in a 1mm sieve so there is nothing smaller than that in the mix, I have looked at the mini pine bark mix but don't like the look of it it looks a little rough and the particles seem too large to me I prefer to sieve my nursery potting mix to get the correct grading.
Craigw

Hi Craig,

This is interesting that you think this is an open potting mix like Waltar's. I don't think it is all that open. It would be good if Waltar could tell us what size particles he is using, as basically the larger the particles the greater the air filled porosity, which is the important component of the pore spaces. I have the feeling he is using something in the order of 5-6mm particles.

Personally I put everything over a 2mm sieve, and the largest pieces are through a 5mm seive. I use 2.2-7mm zeolite, which is predominantly larger particles, sieved composted pine bark extracted from a potting mix, and large perlite, all 1:1:1. This gives me a air filled porosity of 26% in a 10cm pot. I only water once a day below 30C.

It would be interesting to know your air filled porosity.

Gerard said;

think that in general the air spaces will be governed by the size of the smallest particles but perhaps the most important fact is consistency. If particles are all the same size we can expect that the dampness of the soil is similar in all areas of the pot (obviously the centre of the mass will be the wettest) this would help in deciding when it is necessary to water. When particle size varies I would expect smaller particles to be washed to the bottom of the pot, the bottom of the pot would then retain much more water than the surface and increase the temptation to overwater.


Potting mixes are made up of solids and pore spaces, when we water, the liquid is held in the mix by surface tension, gravity tries to pull it out, so yes water does tend to congregate in the bottom of the pot. The amount of air left in the pot after it has drained is called air filled porosity (AFP). This is very important because different plants need different AFP. However, it is large pores which allow air to penetrate deep into the mix, even to the bottom, simply because the pore size is too big for surface tension to hold the water. Yes, fines will wash down and collect at the bottom, and reduce air filled porosity at the bottom of the pot, not necessarily holding more water. Roots do this as well, and is this is one reason for frequent potting. It is best to remove all dust and fines as these clog up the larger pores, reducing AFP, how fine depends on the practitioner, I think 2mm is good. So this is what we are kind of discussing here, getting a feeling for particle sizes. I would like to know what Waltar's size is.

Paul

Paul

[Walter Pall]

My particles normally are from 3 to 4mm.

[craigw60]

Hi Brett, I had friend who found the diatomite how he came across it I don't know but we used to bring pallets of it down from QLD as it was not available in Vic. at that time, the thing which first attracted me to it was the weight, potting trees using granite made them seriously heavy, once I started using it I realized what a great potting medium it is. I was initially advised it would break down after 3-4 years but have never seen it do this and some of my pines get potted very rarely.
Paul, Walter has just told us his particle size is 3-4mm which would roughly correspond with mine I find the diatomite 2-7mm doesn't have too much 7mm in it. The last batch I bought was too fine and a great deal of it was lost in the sieving, as to the air filled porosity that is far too scientific for me, but I do agree that all the fines need to be removed this is critical to good drainage.
Craigw

[NBPCA]

My particles normally are from 3 to 4mm.

Fabulous Walter,

thanks for that. Now I have a bench mark to work with.

Grant

[63pmp]

Walter,

Thanks for posting the particle size, and for following along with this thread.

Paul